Questions and Answers
What is a sea breeze?
A daytime breeze in which cooler air from high pressure over the coastal waters moves onshore to replace heated air rising above the warmer land mass.
What is a land breeze?
A light nighttime breeze which originates over the relatively cool land, flows out over the warmer coastal waters.
What are periods characterized as critical fire weather conditions? (Select all that apply)
What are common weather phenomena in which critical fire weather conditions occur? (Select all that apply)
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What is a cold front?
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What are potentially dangerous cold front characteristics? (Select all that apply)
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What are indicators of cold fronts? (Select all that apply)
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What are foehn winds?
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Which of the following is a common foehn wind in the Western US? (Select all that apply)
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Why are thunderstorms potentially dangerous to firefighters?
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What are dust devils?
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What are firewhirls?
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What are predictive services?
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What is the point of origin?
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What is the head of a fire?
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What does the flank of a fire refer to?
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What is meant by the rear of a fire?
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What are the three main objectives to fight a fire?
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What is the fire perimeter?
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What are fingers of a fire?
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What are pockets of a fire?
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What is an island in the context of wildland fire?
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What is a spot fire?
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What does smoldering refer to in fire behavior?
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What is creeping fire?
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What characterizes running fire?
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What does spotting in wildland fire behavior mean?
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What is torching in regard to fire behavior?
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What defines crown fire?
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What is a flare up in fire behavior?
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What is a firewhirl?
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What is the backing fire?
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What is the flaming front of a fire?
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What is an anchor point in fire control?
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What is a control line in wildfire management?
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What is a fireline?
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What does mop-up entail in fire control?
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What does it mean when a fire is contained?
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What does a controlled fire imply?
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1 chain = ____ feet.
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What are the three elements of the fire triangle?
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What are the three methods of heat transfer?
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What is radiation in the context of fire behavior?
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Define convection as it relates to fire.
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What is conduction in terms of fire behavior?
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A fire is controlled when it is expected to hold under any foreseeable conditions.
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What does topography refer to?
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What is aspect in terms of fire behavior?
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What are the characteristics of a north facing slope?
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What does slope refer to in wildfire context?
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How do box canyons affect fire behavior?
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What are narrow canyons' effects on fire behavior?
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What does elevation refer to?
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What are barriers in the context of wildfire?
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What three characteristics of fuel does fire behavior depend on?
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What are the fuel types?
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What defines fuel loading?
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What are the fuel size classes?
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How does surface area to volume ratio relate to fire behavior?
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What does fuel arrangement refer to?
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What are ground fuels?
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What are surface fuels?
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What are ladder fuels?
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What are aerial fuels?
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What is fuel moisture?
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What does a stable atmosphere refer to?
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What are visual indicators of an unstable atmosphere?
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What is the jet stream?
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What are local winds?
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How do upslope winds behave?
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What characterizes downslope wind?
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What influences wind characteristics in valleys?
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Study Notes
Wildland Fire Behavior Terminology
- Point of origin: Exact place of initial ignition where combustion begins.
- Head of a fire: Fastest spreading side of a fire.
- Flank of a fire: Area adjacent to the main direction of fire spread.
- Rear of a fire (heel): Slowest portion, spreading against the wind or downhill.
- Fire perimeter: Total outer edge of a fire.
- Fingers of a fire: Narrow extensions extending from the main fire body.
- Pockets of a fire: Unburned areas within fire edge, surrounded by fingers or slower burning sections.
- Island: Unburned fuel zone inside fire perimeter.
- Spot fire: New fire ignited outside the main fire perimeter by embers.
- Smoldering: Fire behavior characterized by no flame and minimal spread.
- Creeping fire: Slow-spreading fire with low flames.
- Running fire: Rapidly spreading fire with a clear head.
- Spotting: When fire sends sparks or embers beyond its main ignition zone.
- Torching: Ignition of leaves/foliage of trees from the bottom, typically small groups.
- Crown fire: Fire reaching the tops of trees, may be independent of surface fire.
Fire Behavior and Control
- Flare up: Sudden increase in fire spread or intensity, often short-lived.
- Firewhirl: Vertical vortex of heated air, smoke, and gases from a fire, unpredictable in movement.
- Anchor point: A barrier to fire spread used as a starting position for fireline construction.
- Control line: All constructed or natural barriers plus treated fire edges for containment.
- Fireline: Area of the control line that has been cleared down to mineral soil.
- Mop-up: Procedure of extinguishing near control lines to prevent flare-ups.
- Contained: Fire status indicating that control lines are complete, expecting to prevent spread.
- Controlled: Completion of control lines around the fire, including buffers to manage hot spots.
Fire Triangle and Heat Transfer
- Three elements of the fire triangle: Fuel, air (oxygen), and heat.
- Three methods of heat transfer: Radiation, convection, and conduction.
- Radiation: Heat that can dry or ignite surrounding fuels.
- Convection: Upward movement of warm air and embers creating a smoke column.
- Conduction: Heat transfer through direct contact between fuel particles.
Topography's Role in Fire
- Topography: Arrangement of the earth's features, affecting fire spread.
- Aspect: Slope direction regarding sun exposure; influences fuel moisture and fire behavior.
- Box canyons: Fires in these areas can have accelerated reactions similar to flames in enclosed spaces.
- Narrow canyons: Eddies and strong winds can spread fire across to opposing sides.
- Ridges: Fire may change direction when ridges meet canyons due to airflow.
- Saddle: Wind through mountain passes increases speed and may cause erratic fire behavior.
Fuel Dynamics
- Fuel characteristics affecting fire behavior: Type, loading, and availability.
- Fuel types: Grass, grass-shrub, shrub, timber-understory, timber litter, and slash-blowdown.
- Fuel loading: Weight of fuel per unit area, indicating potential intensity and spread.
- Surface Area to Volume Ratio: Smaller fuels burn quicker due to higher surface area exposed to air.
- Fuel arrangement: The spatial distribution of fuels; can be horizontal or vertical, affecting fire spread.
- Vertical arrangement: Includes ground, surface, ladder, and aerial fuels, contributing to fire intensity.
- Fuel moisture: Determines ignitibility and burning efficiency, affected by weather conditions.
Weather and Fire Behavior
- Fire weather principles: Temperature, relative humidity, precipitation, atmospheric stability, and wind patterns.
- Relative humidity (RH): Levels inversely related to temperature; affects fuel moisture.
- Atmospheric stability: Influences upward air movement; unstable conditions promote fire intensity.
- Indicators of stable and unstable atmospheres: Variations in cloud formation, visibility, and wind patterns often signal fire behavior changes.
- Critical fire weather conditions: Strong winds, low humidity, high temperature, and dry thunderstorms can trigger severe fire risks.
Wind Effects on Wildland Fires
- General winds: Larger scale, resulting from atmospheric pressure systems, usually flowing west to east.
- Local winds: Terrain-influenced winds including upslope and downslope variations.
- Specific wind characteristics: Variability in speed and direction throughout the day significantly impacts fire dynamics.### Weather and Fire Risks
- Warm conditions for the season can lead to increased fire risk.
- Winds can persist for several days, often reaching speeds of 40-60 mph.
- Relative humidity (RH) decreases as winds pick up.
- High wind speeds combined with low RH create ideal conditions for rapid fire spread.
Common Foehn Winds in the Western US
- Chinook Wind: Found along the eastern Rockies and east of Sierra Nevada.
- Wasatch Wind: Occurs on the western side of the Wasatch Range in Utah.
- Santa Ana and Sundowner Winds: Affect Southern California.
- Mono and North Wind: Influence central and northern California.
- East Wind: Present in western Washington and western Oregon.
Thunderstorm Risks for Firefighters
- Winds associated with thunderstorms can shift, altering fire behavior and intensity.
- Rising heat from fires can create strong convection columns, potentially forming thunderstorms.
- Thunderstorms can produce hazardous downdrafts, increasing fire danger.
- Lightning strikes pose additional risks for igniting new fires.
Dust Devils
- Serve as indicators of unstable air conditions in hot, dry weather.
- They typically form over dry ground on clear days with light winds.
Firewhirls
- Generated by intense heat from wildfires.
- Capable of lifting large, burning embers and spreading them beyond the main fireline, causing new spot fires.
- Often develop on the leeward side of ridges, where winds are sheltered.
Predictive Services
- Comprise a team of Interagency Land Management Fire Intelligence Coordinators and Fire Meteorologists.
- Conduct seasonal assessments to evaluate fire risks.
- Provide forecasts for 7-day significant fire potential and monthly outlooks.
- Offer briefings and daily summaries to inform firefighting efforts.
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Description
Test your knowledge on different types of breezes, including sea and land breezes. Understand the conditions that create these daytime and nighttime winds, and explore their speeds and characteristics. This quiz covers essential concepts in meteorological phenomena.